To manufacture a spun yarn from a loose fiber structure, devices are used in which a swirl chamber is provided between a fiber delivery channel and a yarn extraction channel. A fluid is blown into the swirl chamber. This device exhibits in the swirl chamber a guide surface, which delimits the swirl chamber downstream for the purpose of guiding fibers or fiber sectors that are swirling in the swirl chamber, the surface extending in collar fashion around the inlet aperture of the yarn extraction channel. The guide surface may form an angle of at least 30 with the axis of the yarn extraction channel in the yarn extraction direction, and outer areas of this guide surface are at a distance interval from the inlet aperture of the yarn extraction channel that corresponds to at least one tenth of the effective staple length of the fibers that are to be processed.